Disagreements remain on how to share out responsibility for curbing greenhouse emissions between rich and poor nations
Vatican City (AFP) - Pope Francis on Thursday urged the world to act quickly to prevent "extraordinary" climate change from destroying the planet, saying rich countries must bear responsibility for creating the problem, and finance a solution.
In a near 200-page document, the leader of the world's 1.2 billion Catholics blames human greed and consumerism but also business and political figures for the situation "Our Sister, mother Earth" now finds itself in.
"This sister now cries out to us because of the harm we have inflicted on her by our irresponsible use and abuse of the goods with which God has endowed her," he writes in the long-anticipated encyclical.
Arguing that environmental damage is intimately linked to inequality, he says doomsday predictions can no longer be dismissed.
"The earth, our home, is beginning to look more and more like an immense pile of filth."
US President Barack Obama praised the pope's call for action and said the United States should lead global efforts to cut carbon pollution and bolster clean energy sources.
"I welcome His Holiness Pope Francis's encyclical and deeply admire the pope's decision to make the case -- clearly, powerfully and with the full moral authority of his position -- for action on global climate change," Obama said in a statement.
Activists also hailed the charismatic Argentinian pontiff's intervention as a potential game-changer in the debate over what causes global warming and how to reverse it.
"Everyone, whether religious or secular, can and must respond to this clarion call for bold urgent action," said Kumi Naido, Greenpeace's international director.
Environmentalists hope the message will increase pressure for binding restrictions on carbon emissions to be agreed at global talks in Paris at the end of this year.
Christiana Figueres, the top UN climate change official, said Francis's call "should guide the world towards a strong and durable universal climate agreement in Paris".
But climate change sceptics dismissed the document's argument that the phenomenon is primarily man-made and that humanity can reverse it through lifestyle changes including an early phasing-out of fossil fuels.
US presidential candidate Jeb Bush, a Catholic, said the pope's guidance would not affect his policies should he be elected.
"I don't go to mass for economic policy or for things in politics," he said.
Christopher Monckton of the Heartland Institute said on Twitter that the pope's stance ignored the interest of the poor in having access to cheap energy, saying he "has sided with the rich profiteers of doom".
Separately, US government scientists on Thursday revealed figures showing that last month was the hottest May on record, with global air and sea surface temperatures 1.57 degrees Fahrenheit (0.87 Celsius) higher than the 20th century average.
- Fast track to disaster -
The encyclical references the arguments of the sceptics by acknowledging that volcanic activity, variation in the Earth's movements and the solar cycle are factors in climate change.
But it maintains that "most global warming in recent decades is due to the great concentration of greenhouse gases released mainly as a result of human activity".
And it leaves no doubt that Francis believes the world is on a fast-track to disaster.
"If present trends continue, this century may well witness extraordinary climate change and an unprecedented destruction of ecosystems, with serious consequences for all of us," he writes.
Bemoaning the "remarkable" weakness of political responses to this, Francis accuses sceptics of cynically ignoring or manipulating evidence.
"We know how unsustainable is the behaviour of those who constantly consume and destroy, while others are not yet able to live in a way worthy of their human dignity," he adds, saying the time has come for parts of the world to accept decreased growth.
The consequences of climate change, he argues, will include a rise in sea levels that will directly threaten the quarter of the world's population that lives near or on coastlines, and will be felt most acutely by developing countries.
Highlighting warnings that acute water shortages could arise within decades, he writes that "the control of water by large multinational business may become a major source of conflict in this century".
- 'Structurally perverse' -
One of the strongest themes in the encyclical is that rich countries must accept responsibility for having caused climate change and should "help pay this debt" by cutting their carbon emissions while helping the developing world adopt sustainable forms of energy generation.
"The land of the southern poor is rich and mostly unpolluted, yet access to ownership of goods and resources for meeting vital needs is inhibited by a system of commercial relations and ownership which is structurally perverse," the pope writes in perhaps the most radical passage of the document.